The present invention relates to a reader for a digital trip device associated with a current breaking device.
In the field of current breaking devices, for example circuit breakers for electrical motors, the development of new techniques using microprocessors has led to trip devices being produced which enable the tripping conditions to be accurately determined taking a large number of parameters into account, for example to enable short delay trips, or long delay trips in correspondence with predetermined complex graphs to optimize the operation of the motor and its tripping.
Thus, user demand has led to the appearance of trip devices providing a large number of possibilities and which consequently require in practice the presence of a display means or read-out means to indicate the statuses of the settings made and the currents flowing in the motor power supply, these currents being taken at the level of the circuit breaker.
A drawback to such elaborate trip devices becoming generalized is their relatively high cost. Thus, sophisticated trip devices of this kind are in practice limited to associations with high-power circuit breakers associated with high-power motors, which are therefore expensive, for which it is worthwhile providing a sufficiently elaborate protective device (tripping). For medium power motors, users hesitate to fit themselves with sophisticated trip devices which do not seem sufficiently worthwhile compared to the investment they represent.
An object of the present invention is to enable sophisticated trip devices for circuit breakers to be used, these trip devices providing the functions at present existing for high-power applications but achieved in such a way as to be less expensive.
The initial idea for the present invention results from a cost analysis of the sophisticated digital trip devices available at present. With microprocessors being produced on a very large scale and being easy to program, the latter no longer constitute a determining factor in the cost of a digitial trip device. Paradoxically, the cost of the alphanumerical read-out accounts for a large part of the cost of the trip device.
If, however, this read-out is replaced by a system of indicator lamps or abolished, the trip device is no longer of any great interest to the user. Indeed, to take advantage of everything a sophisticated trip device has to offer, it is necessary to know what settings have been made, and also to be able to accurately detect the currents flowing in the circuit breaker supply lines in normal operation and when a trip occurs.